セラミックスのカーボン被覆

Abstract

Carbon coating of ceramic particles were successfully performed by a simple process, i.e., heat treatment of powder mixture of thermoplastic carbon precursor (such as poly(vinyl alcohol), PVA) and ceramic s (such as MgO, TiO_2, etc.). The experimental results obtained since 1985 were summarized. Preparation conditions of mesoporous carbons from carbon-coated MgO through the dissolution of MgO by diluted acid were established. Mesopore size could be controlled by MgO precursor. Carbon-coated TiO_2 was found to give various merits for photocatalyst, hybridization of adsorptivity with photoactivity, suppression of phase transformation from anatase to rutile, fixation by using organic binder. From the mixture of SnO_2, MgO and carbon precursor, the dispersion of metallic Sn nanoparticles in porous carbon was successfully performed. In these carbons, some space neighboring Sn particle was always formed after the dissolution of MgO particle, which was advantageous to absorb some expansion and shrinkage due to alloying of Li into Sn. From the mixture of K_2WO_4 and K_2MoO_4 with carbon precursor, carbon-coated WC and Mo_2C were synthesized, which gave a high volumetric high capacitance in electrochemical capacitor. From the mixture of (NH_4)_<10>W_<12>O_<41> with PVA, on the other hand, carbon-coated W_<18>O_<49> could be prepared, which had a photocatalytic activity in visible light. The mixtures of Fe_2O_3 and NiO with carbon precursors gave either carbon-coated Fe or Ni, in which graphite crystals formed even at 900℃. Carbon coating of ceramic tiles gave a possibility to produce Japanese roof tile with a new process, which was completely different from conventional one.